( 5' ) 



It c'oiisisis of (Iii-cc (iilx's J. /;. (\ [Kciii. (liuli, iiilcriial (liaiiiclcr 



1.8 cm.) which coiinniiiiic-ilc l>v means ol' co ctiiiu liihcs. To ihc 



tube /'i/', :i ,iiiiiss l;i|» wilh a xcrv wide horc (.5 or (i lu.iii.j is 

 attached. The z,iiic amal.uam is iiilrochiccd inio J aiui ihc |)latiiiiiiii 

 wire JH is then fused into il. J and 11 also /', arc now lillcd w hh 

 the zinc sulphate solidion after llic Uore of the lap lias hccii pliiiii-cd 

 witli fat-free cottonwool |»re\ions|y sucked in llie same zinc sulphate 

 solution. While the laj) is slill closed, ihe saluraled copper sulphate 

 solution is poured iiHo Tand also iido /'^. The cell is now closed 

 with the iiulia-i'id)l)er corks A', A'^ and A'.,. Thi-ouiih A'., is introduced 

 a thill g-Iass tube reachinj>' Just below the cork. Throuuii this lube Ihc 

 co[)per elcM'trode A' may be iidrodiiced inio ihe solulion when ihe 

 measurements take |»lace. The whole apj)aratus is now plunucd as 

 deep as possible in a thermostat (JTr). if rccjuired ihe lap nia\ be 

 opened or closed by means of Ihe \\(»o(len rod («11. 



By the intrcxluction of Ihe tid)e B Ihe possibilily of conlacloflhe 

 zinc electrode \vith Ihe co|»per sul|>liale solulion is (pule e.\clude(l. 

 Even if a trace of cop|»er sulphate has difhised into Ihe lower jiart 

 of ]j (if Ihe copi)er solution is lighter than the /.inc solulion, Ihe 

 former will float in /i on Ihe laltei-) we ne\ cr lind a trace of cop] xm- 

 in the tube J. In the tiiial experimeids, Ihe measni'cmenls lasled so 

 short a time thai as a I'ule no copjiei- dilfused e\-eii into /A 



7. After j^reliininary ex|)ei-iinents had shown that Ihe cells cainxjl 

 be reproduced when we make use of co|)per clecli'od(>s which haxc 

 been cleared with nitric acid, we aflei'wards followed the direction 

 of Wkigiit and Fi.kmincj who electrolylically co\er Ihe coj)[)er electrode 

 with ji layer of coppei* immediately before Ihe measurement. For 

 this |)urpose we used the bath descriluMl by Okttki, ') for llie coppei' 

 coidometer. After being coj)per|>laled Ihe electrode was i-insed wiih 

 dislilletl water and dried \vith cottonwool. Il was liien al once put 

 through the lube iido the cell. We always lake cai-e llial oidy llie 

 eleclrolylically copper [dated |)art of Ihe electrode gels into contact 

 wilh llie li(pnd. 



(S. The Vj. M. V. of the c(dls was delermined by llie compen- 

 sation method of Po(i(JKNi)OKi'F. As workinu- eell we used a storaji'e 



') Elect ro(;lierai.';cl 10 Ucbungsaiil'gabcn (Halle b^'.>7) pag. ."). All coppor oleclrodes 

 \vero always copperplalod during 10 miniUes willi llic same cuirojil-slrengtli (0.15 

 ampère) (or (len.sily) and at the same temperature. \Vc liavr also hied, IjiiI nnsne- 

 ces.sfiilly, to work with copper amalgam. As lo copper amalgam, compare Pi:ttkn- 

 KOFEK, DiN«LER l\)lyteclmisclies Journal 109, 441 (184S) and v. CJersuelm. Ibid. 147, 

 4G2 (1858). 



